In most cases of diabetes, various genes and environmental factors are involved. Not in monogenic diabetes, where the causes are mutations in just a single gene. Between 25% and 45% of family members or patients with monogenic diabetes do not present alterations in any of the genes that have been put forward to date as possible causes, and so new candidate genes have had to be identified.
Biochemist Ms Intza Garin has made advances in this direction, in a thesis defended at the University of the Basque Country (UPV/EHU) and entitled "The search for new genes involved in monogenic diabetes." The research by her work team has also been reflected in publications such as The Journal of Clinical Endocrinology & Metabolism, in December 2010.
Monogenic diabetes is considered a rare disease, making up only 1% to 3% of all cases of diabetes. There are two types: neonatal and Maturity Onset Diabetes of the Young (MODY). In most cases, it is a hereditary disease that appears when one of the parents passes on the mutation in one of their genes to their offspring, although there are also cases in which such a mutation is generated spontaneously. Garin believes that these alterations may be produced in genes that have not been associated with this type of diabetes to date. Thus, she set out to identify hitherto unknown causes to the disease by studying affected families and patients.
Chromosome 8 and more clues
Garin carried out an analysis of the complete genome, while not prove useful in determining which new genes might be responsible for monogenic diabetes, was able to throw light on chromosome 8. Although the search for mutations here did not conclude with the discovery of a causal genetic variant, the data obtained confirm that the 8p12-p11 region of this chromosome is a candidate for being a gene responsible for this rare disease.
As a consequence, Garin's thesis may well be a new, hitherto unknown, starting point in the quest for the causes of monogenic diabetes. The research also came up with other clues which could help with future studies.
Concretely, the researcher stressed in her research that the analysis should not be only focused on the analysis of the codifying region of the gene, but should include the non-codifying regions (introns and 5' and 3' UTR regions), given that variants were also observed in these zones. Likewise, Garin recommends analysing the possible alterations as regards the number of copies of the sequence, because, despite it not having been the case in this research in concrete, it may well be an indicator when studying other candidate regions. Finally, as regards neonatal diabetes, the evidence points to the age of diagnosis, the weight at birth, the ponderal index and the permanent or transitory form of the diabetes as being pointers in the genetic study of the ailment.
- Q. Zhou, I. Garin, L. Castano, J. Argente, M. T. Munoz-Calvo, G. Perez de Nanclares, S.-L. Shyng. Neonatal Diabetes Caused by Mutations in Sulfonylurea Receptor 1: Interplay between Expression and Mg-Nucleotide Gating Defects of ATP-Sensitive Potassium Channels. Journal of Clinical Endocrinology & Metabolism, 2010; 95 (12): E473 DOI: 10.1210/jc.2010-1231
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